The specific purpose of this research project is to characterize the receptor for interleukin 2 (IL-2) on surface membranes of normal and malignant human lymphocytes. We plan to use two probes for these studies: (1)\purified IL-2 and (2)\monoclonal antibodies (MoAbs) reacting with the receptor for IL-2. Near-complete purification of IL-2 can be devised by the researcher. A new series of affinity matrices has also been identified and will be applied to the complete purification of IL-2. Binding studies with radiolabeled IL-2 molecules will allow the identification and characterization of IL-2 receptor on activated normal T-lymphocyte subpopulations as well as cells from patients with lymphoproliferative malignancies. We will examine the kinetics of "down regulation" and degradation of IL-2: receptor complex and reexpression of the IL-2 receptor. MoAbs to IL-2 receptor will allow further characterization of the receptor and will provide a source of IL-2 receptor ligands in milligram quantities. These MoAbs will be used to screen normal and malignant T-lymphocyte subpopulations for both quantitation differences in IL-2 receptor content as well as qualitation differences (KD; effects upon metabolism). Functional studies of the IL-2 receptor will be carried out with agonistic MoAbs that stimulate the receptor, imitating IL-2 activity, and with antagonistic MoAbs that block the receptor, inhibiting lymphoproliferation. The MoAbs will also allow initial affinity purification of the receptor. This project has importance for: (1)\understanding the biological role of IL-2 receptors in the control of normal and malignant lymphoproliferation and (2)\identifying quantitative and qualitative differences in IL-2 receptors on normal and malignant human lymphocytes. (CS)